|The Nature of Star−formation in Halos: HI Bridges and Streams in the MW and the M81-M82 group
|We have now reached a relatively mature understanding of the physical processes that regulate the ISM in galaxies, but we are woefully ignorant of the details of the cycles between gas in and outside of galaxies. This is unfortunate because understanding the gas physics in a wide variety of environments is the key to determining the r^ance of the physical mechanisms that have been invoked for driving galaxy evolution -- from the feeding of star formation through accretion of cold gas to the regulation of star formation through the mechanical energy ejected by massive stars and AGN. To help to overcome our ignorance about the nature of star formation in different environments, in this case in galaxy halos, we propose to use PACS to observe [CII] in many selected regions of the bridges of HI in the nearby group of M81 and in the Magellanic stream, two of the nearest intergalactic gas flows. These regions are excellent targets for this type of study because it has a wide range of HI column densities and stars have recently formed in the gas flow between its galaxies. In response to the comments of the OT1 panel, the Magellanic stream was added as a foil to the M81 group in that it has scant evidence for recent star formation. [CII] is the main coolant and an excellent tracer of the cold neutral medium in galaxies. By combining these data with dust maps from Spitzer, Herschel, HI and H-alpha observations, we will investigate the mass balance between the warm and cold neutral medium to constrain the role of turbulence in regulating this balance, which is key to the cooling and fragmentation of gas and to regulating star formation. Investigating the nature of star formation in a halo of a galaxy or group is one of the critical first steps in understanding what occurs during the cosmological accretion of gas and thus help determine what processes drive the evolution of the ensemble of galaxies.
|Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
|Publisher And Registrant
|European Space Agency
|European Space Agency, 2013, OT2_mlehnert_2, SPG v14.2.0. https://doi.org/10.5270/esa-88ywt56